This disclosure relates to a display device, and particularly it can be applied to a display device provided with a thin film transistor using a silicon semiconductor film and a thin film transistor using an oxide semiconductor film.
Semiconductors of thin film transistor (TFT: Thin Film Transistor) are classified by the purpose of the use: such as amorphous silicon, polycrystalline silicon, and oxide semiconductor (for example, Japanese Unexamined Patent Application Publication No. 2015-144265 and its corresponding US patent application Publication No. 2015-0187952). A thin film transistor using polycrystalline silicon is suitable for a high functional display device formed integrally with a driving circuit because of having high field effect mobility. A thin film transistor using an oxide semiconductor is suitable for a pixel switching element because of having a small leak current, at the non-conductive time.